Abstract

Negative differential resistance devices, based on two similar AlAs/GaAs superlattice structures, were fabricated using a standard selective etching and integral heat sink technology and evaluated in a resonant-cap full-height WR-15 waveguide cavity. Devices from both superlattice structures generated comparable output powers in the fundamental mode at 59–71 GHz. The best devices yielded (with corresponding dc-to-RF conversion efficiencies of ) around 63 GHz. In a second-harmonic mode, these devices yielded up to 14 mW (1%) at 133 GHz. Higher harmonic frequencies were also observed with powers of at 190 GHz and at 260 GHz. The highest observed dc-to-RF conversion efficiency was 5.1% at 62.8 GHz.

Received 12 September 2008Accepted 10 October 2008Published online 05 November 2008

Acknowledgments:

The devices were fabricated in the Michigan Nanofabrication Facility. The authors thank George I. Haddad, University of Michigan, for providing access to these cleanroom facilities. This work was in part supported by the UK Engineering and Physical Science Research Council. The authors would also like to thank Robert E. Miles for helpful discussions.